The longer I practice, the less I seem to know, so I recently enrolled in an online class about tick-borne diseases. The first lecture focused on Lone Star ticks and American Dog ticks.

Afterward, I emailed Dr. Sam Telford from Tufts inquiring whether Lone Star ticks had reached the Vineyard. He said he had collected a few on Chappy a couple of years ago and one or two near Squibnocket, but was not convinced there was an established population. “Established” means the ticks reproduce and persist on site, rather than simply arriving as occasional hitchhikers on migrating birds or traveling pets.

“We have known about them since the early 1980s,” Dr. Telford said, “so they can overwinter successfully in coastal New England weather. I found a lot of nymphs and adults…on Cuttyhunk last year but do not know whether it is an established population. I suspect that it is.”

Lone Star ticks are so named because the female has a silvery-white spot smack in the middle of her back that looks like a star. Although historically from southern and south-central states, the Lone Star is on the move and has been found as far north as Maine. Uniquely aggressive, they will travel long distances to actively seek out hosts, happily feeding on many species, including dogs, cats, birds, rodents, deer — and humans. Preferred habitat is wooded areas with brush and along streams.

American dog ticks, a.k.a. wood ticks, are smaller with an irregular white pattern on the back right up close to the head. They like grassy meadows and woods, and they feed on a wide range of mammals. Both Lone Star and American dog ticks are known to transmit Rocky Mountain Spotted Fever (RMSF).

The name Rocky Mountain Spotted Fever is a bit of a misnomer. Although first identified and studied in the Rocky Mountain region, this disease, caused by the organism Rickettsia rickettsii, occurs throughout the United States, including on the Vineyard where it may be carried by several types of ticks. In people, early symptoms may include high fever, chills, headache, light sensitivity, nausea, vomiting, abdominal pain, loss of appetite, and fatigue. Later a red-spotted rash may develop on arms and legs, spreading to hands, feet, and torso. In dogs, signs may include sudden fever, loss of appetite, enlarged lymph nodes, muscle or joint pain, and neurological abnormalities, but no spots.

Unlike some of the other tick-borne diseases, RMSF is never a slow, chronic disease. It hits hard and fast. Left untreated, Rocky could die within two weeks, so if we suspect RMSF, we immediately prescribe appropriate antibiotics. Most dogs improve quickly and are immune to reinfection.

So Rocky is getting medication and doing great. Your worries are over, right? Wrong. RMSF is not directly contagious from dog to human but, the fact is, you go where Rocky goes. And wherever Rocky has been, he picked up a tick that transmitted RMSF. If untreated, 30 percent of human cases of RMSF may be fatal. Even with treatment, there may be five percent mortality.

Our pets are sentinels, the proverbial canaries in the coal mine, alerting us to the presence of these dangerous tick-borne diseases. And it’s not just RMSF and Lyme. Consider ehrlichiosis and anaplasmosis — a confusing array of related organisms carried by different ticks that cause slightly different illnesses in different species.

In people, there’s Human Monocytic Ehrlichiosis (HME) caused by Ehrlichia chaffeensis, carried primarily by the Lone Star Tick. Then there’s what used to be called Human Granulocytic Ehrlichiosis (HGE) now called Human Granulocytic Anaplasmosis (HGA) caused by the organism that used to be called Ehrlichia. equi, now called Anaplasma phagocytophilum. In dogs? Depending on geographical location, Rocky can get Ehrlichia canis, causing Canine Monocytic Ehrlichiosis, carried primarily by the brown dog tick, or Anaplasma phagocytophilum, (the same bug that causes HGA) carried primarily by Ixodes ticks, or Ehrlichia ewingii, common in places like Missouri and Oklahoma. It’s all very complicated.

At least when it comes to Lyme disease, we know that classic bull’s-eye rash is a sure indicator, right? Wrong again. Although the Lone Star tick doesn’t transmit Lyme, its bite can cause an identical bull’s-eye rash, often associated with fever, headache, stiff neck, and muscle pain. It’s called STARI (Southern Tick-Associated Rash Illness) and luckily tends to be much milder than Lyme disease. The cause has not been identified, although in some patients the organism Borrelia lonestari has been isolated. Should the Lone Star tick ever permanently settle here in paradise, it can also transmit tularemia, another Island specialty.

“Lord help us if the Lone Star tick gets established on Martha’s Vineyard,” Dr. Telford said. “All three stages depend on deer, all three stages aggressively attack people. They are worse than the worst dog tick infestations…you can get dozens on your clothes all at once, [and] they have eyes and will actively come to you. They are very fast. In comparison, dog ticks tend to take longer to attach and their larvae and nymphs never attach to people. Even worse is the ‘seed tick’ phenomenon,a batch of eggs will give about 6,000 larvae and these occur in a cluster…if you are unlucky and step in it, you could literally get dozens of attached larvae. Little chance of infection, but the bites are very itchy. They are, unfortunately, a pest for dogs and cats. Even more reason for Frontline and other topicals.”

So listen up, you Island folk. You know all the measures you should take to protect yourself and your pets from ticks. If you have a question about tick-borne disease, human or pet, speak with your physician or veterinarian. And if you find an unusual-looking tick with a silvery-white star smack dab in the middle of her back, collect it, and contact the Tick-Borne Illness Reduction Initiative through your town’s Board of Health.

Now go tuck your pants into your socks and be sure Rocky is wearing a good topical tick control product.